Primary care physicians are burdened by the complexity of the care that must be delivered to patients with HIV infection, the time required for care and the difficulty of keeping abreast of a rapidly changing knowledge base that is the foundation for that care. We plan to use the computer to ease the burden of care by monitoring each patient's treatment, by suggesting alternative care plans when appropriate, and by providing an integrated information environment. This knowledge-based medical record system for the care of patients with HIV-related illness (KBMR-HIV) will provide physician reminders, directed access to the biomedical literature, information on research protocols, information about community resources, and information about cost-effective strategies for the management of common problems. In addition, the system will collect data and information that will be of immediate use to those caring for the patients and will be of future use to those interested in aggregation of longitudinal data for the purpose of clinical, epidemiologic and policy related investigation. Patient information from KBMR-HIV will be transferred into ClinQuery, a data management tool developed to facilitate rapid exploration of aggregate clinical data base. ClinQuery provides for confidential access to patient data while inviting exploration of this clinical data. This data base will contain information about patients who have been treated in a variety of care settings (home, ambulatory, and inpatients), by a variety of care providers (staff physician, intern, resident, and nurse practitioner), and by a variety of protocols. We hypothesize that physicians who use KBMR-HIV will indicate they are more satisfied with the care they are giving to patients with HIV infection. We will administer a series of questionnaires to help assess their satisfaction and we will analyze clinicians' adherence to agreed upon standards of care to help assess their effectiveness. We will also evaluate the number of admissions, the interval between admissions, the total charges for hospital care, the total charges for all care (impatient and ambulatory), the number of ambulatory visits, the number of invasive procedures, the number of opportunistic infections, and other outcome measures among patients who are cared for by clinicians with access to KBMR-HIV, to assess the effect, if any, on the quality of care.